The present invention relates to an improved internal conduit sealing member and in particular, to a sealing member made from an elastomeric material and having a pair of sealing segments located at the outer periphery of the elastomeric seal which sealing segments includes a plurality of compressible ribs and inner and outer restraining members. Each rib segment is located under an expansion band to provide seals for pipe used in carrying various fluids. The invention also relates to novel expansion band for compressing said internal sealing member and, in particular, to a radiused expansion band in combination with a locking element positioned between an outer restraining member and adjacent rib.
It has become known to use cuffs or sealing members internally of a conduit to seal joints or damaged areas of a conduit to prevent infiltration into or leakage from the conduit or pipe. Conduits of this character typically carry water, wastewater, sewage, natural gas, petroleum and the like. Since these pipe are normally located underground, they are susceptible to damage from the environment, corrosion, cracking or leaks at the joints. In many cases it is not possible to expose or excavate the pipe for repair because of the necessary excavation would disrupt highways, building and the like. In these cases it has become acceptable to use trenchless, internal joint or damage sealing means. It is not uncommon to internally seal or repair pipes of diameters from 14 inches to 216 inches using elastomeric sealing materials. See, e.g. U.S. Pat. No. 4,685,704. The seals are placed within the pipes by skilled technicians who traverse the pipe to the damaged or leaking area.
The sealing installation process is relatively uncomplicated. The elastomeric seal generally is circular in nature, but can be dimensioned to assume other pipe shapes. The elastomeric material of the seal is typically selected for the type of material flowing through the pipe. For example, ethylene propylene diene monomers rubber is used for waste water and potable water, butadiene acrylonitrile rubber is used in natural gas applications. Normally, the seal is provided with internal annular recesses designed to accommodate metal bands which are made from stainless steel, carbon steel, or special alloys. Once the seal is positioned over the joint or leak by hand or pneumatic means, the bands are placed in to the annular grooves. A special hydraulic press is used to expand the band in the groove to compress the seal against the pipe. Special wedges or inserts are used to maintain the position of the band to maintain compression and provide a fluid tight seal.
Typically, the seals are manufactured by extrusion through a die containing the desired profile or molded, however, this is relatively expensive. The seal is extruded in the form of a belt with a cross-section in which the profile the sealing ribs located adjacent to but spaced apart from the edges, and under the band accommodating grooves. A web membrane is located between the rib sections and can be of a varying lengths to accommodate both joints and areas subject to damage or leakage. The belt is cut uneven to fit the inside circumference of the pipe, tube or tanks. Similarly, belts can be joined by adhesive, overlapping or vulcanizing to form a continuous seal that is circular or in other geometric shape.
While the use of internal sealing means such as disclosed in U.S. Pat. No. 4,685,704 afford more efficient and cost effective repair, such repairs are not inexpensive. It is therefore desirable to make the repair as well as the seal itself as trouble free and long lasting as possible. Accordingly, it is an object of the present invention to provide an internal pipe seal which can be installed using conventional hydraulic presses and bands, but provides a sealing profile which affords more effective sealing than current seal profiles. It is a further object of the invention to provide a novel seal, seal profile, and expansion band that locks in place when subjected to high velocity or low velocity flow of material transported through a pipe or struck by debris moving within a pipe or conduit. It is also an objective of the invention to provide an external seal member having a structure that controls the cold flow of elastomeric material under compression of the expansion bands.
The present invention comprises an internal conduit seal for sealing a damaged conduit or conduit joint which comprises an elongated molded or extruded elastomeric sealing member. Generally, the elastomeric member has a length which is substantially equal to the internal circumference of the conduit to be repaired and has a width adequate to accommodate the span of the joint area which is damaged. Generally, however, the elastomeric seal member is not wider than about a meter since wider seals can be formed by overlapping multiple elastomeric members. The elongated elastomeric member includes first and second spaced apart sealing segments that co-extend the length of the elastomeric member. Each sealing segment is positioned adjacent a respective edge of the elastomeric member and comprises a plurality of juxtaposed sealing ribs and an inner and outer restraining member. In the preferred embodiment three parallel spaced apart longitudinal ribs are provided between the inner and outer restraining members.
The ribs in each of the first and second sealing segments depend from the base of the elastomeric member and terminate in a tapered end portion. In the preferred embodiment, the tapered end includes at least one groove forming pair of substantially pointed sealing edges. In the preferred embodiment, this groove is preferably xe2x80x9cVxe2x80x9d-shaped approximately 2.5 mm in depth. However, if more than one groove is provided, that is two or more, the depth of the grooves on a rib decrease in number with multiple grooves the cross-section profile of the rib appears as a serration. The spacing between the ribs and the restraining members is such as to permit the cold flow of elastomeric material during compression. The respective restraining members depend from the base of the elastomeric material a distance which is preferably slightly less than the ribs. The end portion of the restraining members are preferably arcuate, but may have other shapes such rectangular or flat.
Positioned along the length of the elastomeric member and on the reverse side of the sealing segments and substantially overlying the respective sealing segments are first and second associated band grooves. The associated grooves are dimensioned to accommodate expansion bands in a flush compressive fit. In practice, conventional expansion bands can be used. However, the present invention provides a radiused expansion band, which can be used in combination with the locking element of another preferred embodiment.
In one embodiment of the invention, a continuous or segmented locking element is positioned in the space, between the outer restraining members of each sealing segment and the associated first adjacent rib to such restraining member. Preferably, the locking member comprises a spring wire having knurled or edged sections along its length. The diameter of the locking element if circular or oval or its depth if rectangular or a polygon is less than the uncompressed height of the rib between which it is juxtaposed. The locking element provides grip between the elastomeric seal member when in compression and the conduit so as to resist movement when in the sealing position. In this embodiment, it is particularly advantageous to utilize the radiused or convex expansion band. With such use the force vectors through the seals segments forces the locking element into the seal member and almost a locking engagement with the conduit.
In another embodiment, arcuate edge elements are molded or extruded along the length of each edge of the elastomeric member. The arcuate edge elements are formed with an outwardly extending flange and an arcuate return adjacent to the respective outer restraining member. The arcuate extension is designed to extend outwardly from the body of the elastomeric member under compression of the latter during installation to form tapered surface from the conduit to the surface of the elastomeric member having the expansion bands. In this manner a smooth flow profile is present to provide a substantially laminar flow of fluid.
The sealing member of the present invention provides a substantially enhanced seal means for internal sealing of conduit. In addition, the invention is cost effective in providing long term protection against further leakage. Other advantages of the present invention will become apparent from perusal of the following detailed description of presently preferred embodiments of the invention taken in connection with the accompanying drawings.